Political leaders are generally highly skilled manipulators of people. When a nation is troubled, afraid, or vexed - such as Germany after Versailles, Cambodia after the Vietnam War impacted on it, the Yugoslav republics as the country fell apart, etc. etc., the people become easier to manipulate and it becomes easier for a strong leader to tease a people's murderous and nationalistic instincts to the surface.
Yes, fear lays people open to unreasonable thinking and behaviour. They will accept many things they'd not accept were they living in peace and contentment. This is of course one reason why nation are put against nation, and people put against people by these very political leaders. It keeps us down, and them in power.
However, such things happen within the ranks of the people too. Any situation where you have leaders and non-leaders, you have the opportunities for fear and divide and rule. Offices and businesses can be appalling places to spend time in for example.
But more key to this all is that the leaders of politics, or business, or sport, or local groups, or anywhere humans conglomorate into groups, get the platform to use language. They own the medium. The people are forced into a listening role, while the leaders can do all the manipulating because they have the speaking role.
But in other situations the group leader will not abuse his/her position, and instead use it for positive enhancement of the group. You will know what i mean when i say i do this in my line of work. Or at least, if i'm to be effective, then i have to follow this path.
Pertinent to the thread is will everyone act in the same way if they have the same opportunity. I say no! From experience.